/Engine/Source/Runtime/SignalProcessing/Public/DSP/SpectrumAnalyzer.h
Actual FFT size used. ForFSpectrumAnalyzer, we never zero pad the input buffer.
enum EFFTSize { Default = 512, TestingMin_8 = 8, Min_64 = 64, Small_256 = 256, Medium_512 = 512, Large_1024 = 1024, VeryLarge_2048 = 2048, TestLarge_4096 = 4096, }